I. Field of the Invention
The present invention relates generally to truck bodies and primarily truck bodies dedicated by design to the collection, storage and discharge of refuse which are of a rear discharging type and are provided with a vertically, pivoting rear tailgate. These bodies include rear-loading, front-loading and many side-loading collecting models.
II. Related Art
Rear discharging refuse collection vehicle bodies of all types in the class of interest include one or more generally hollow storage compartments and are characterized by a rather large, heavy top pivoting tailgate assembly. The tailgate in the normal or closed position covers the aft portion of the storage compartment and is typically top hinged to pivot open and clear of the aft portion of the storage compartment to allow complete discharge of the contents without interference. Discharge is typically accomplished by a hydraulically-operated ejection blade which uses a long rearward directed power stroke to sweep the contents out through the open end of the storage compartment while the tailgate is fully opened.
The tailgate is normally opened by the combined efforts of a pair of oppositely disposed single-acting hydraulic cylinders which are connected between the sides of the truck body and the corresponding sides of the tailgate such that when the cylinder rods are fully extended, the tailgate is fully open.
FIG. 1 depicts a fragmentary view of the aft portion of a typical prior art rear-loading refuse vehicle generally at 10 in which the rear-loading refuse truck body 11 is carried by a heavy truck chassis 12 which may be of a conventional class of refuse-hauler chassis and includes a steerable front axle assembly complete with wheels, etc., which are well known and need not be illustrated for present purposes. The tailgate assembly as shown at 13 is cantilevered and extends a distance behind the rear wheels (14). The tailgate assembly is drawn in a closed position and alternatively illustrated in a fully open or refuse discharge position in phantom. As can be seen from FIG. 1, the tailgate assembly is a relatively large, heavy and cumbersome mechanism which also forms the closure to the refuse storage compartment of the truck body. The tailgate section 13 includes rather heavy, substantially vertical primary structural members on each side as at 15 by means of which the tailgate section is hinged to pivot about a pair of large pivot pins at 16. The tailgate assembly consists of a plurality of structural brace members connected by welded sheets to form a rather substantial structure. A pair of manually-operated latching mechanisms are provided, one of which is shown at 23.
The refuse storage compartment itself is of a well-known type and includes a compacting system operated by a pair of spaced cylinders, one of which appears at 17 and an ejection plate (not shown) which, during collection efforts, serves as a reaction member against which the refuse placed initially in the tailgate is compacted. The ejection plate is moved toward the front of the truck body by the pressure of accumulating compacted refuse which exceeds the resistance of the blade until it reaches the forward end when the storage container is filled. Thereafter, during the discharge sequence, a hydraulic ejection system is operated that serves to reverse the process forcing the blade rearward to sweep the entire truck body clean from fore to aft. This system is activated when the tailgate assembly is complete raised to accomplish discharge of the refuse at a landfill.
The tailgate assembly itself is opened or raised by a pair of single-acting hydraulic cylinders, one of which is shown at 22, and includes a cylinder rod 18, pivotal rod end connection 19 connected to the tailgate frame and a pivotal blind end connection connected to the main container body strut 20 which abuts tailgate strut 21 when the tailgate is fully closed.
During inspection and many maintenance routines, the tailgate raising cylinders may be partially extended (normally the tailgate is opened about one-fourth of the way) and blocking devices inserted between the tailgate assembly and the open truck body container to proclude the possibility of any unscheduled closure of the tailgate as by loss of hydraulic pressure. Such devices may be in the form of pivoting strut members connected to the tailgate which have free ends received in recesses provided in the truck body structure or other members positioned manually by workers. These devices have been used successfully in the past to prop-open tailgates. However, additional positive locking devices associated with the tailgate operating mechanism itself, deployable to positively prevent retraction of the cylinder rods during those times when it is necessary that the tailgate be maintained in a partially opened position would be a highly desirable addition.
By means of the present invention, there is provided a manually operable system associated with each tailgate operating cylinder that deploys a locking insert member or locking collar assembly between the rod end of the cylinder and the rod end-tailgate pivot connection member to prevent further retraction of the cylinder rod when the locking collar assembly is wedged in place. The locking collar assembly is pivotally mounted to the tailgate toward one end and operated manually using an extended operating rod and handle system member pivotally attached toward the other end of the member so as to pivot it in and out of place. A locking system holds the handle in position (and so the collar) when the collar is deployed prior to lowering the tailgate to wedge both collars in place.
The locking member may take the general form of an elongated collar having an open end and side directed toward the cylinder and rod and which, when pivoted into position, fits over and captures an extended portion of the rod with the proximal portion then extending through the opening in the end of the collar to the point where it emerges from the rod end of the cylinder, the side and end gaps being greater than the diameter of the cylinder rod but less than that of the outer diameter of the cylinder. The interior of the collar may be provided with contact buttons of a non-abrasive plastic material such as nylon, in places to prevent any damage to the cylinder rod by scratching of the surface. When the tailgate is lowered slightly, the cylinders retract, and each locking insert collar becomes wedged along the rod between the rod end connection to the tailgate and the rod end of the cylinder, thereby preventing further retraction of the rod into the cylinder.
The handle is provided with a pin system which can be utilized to support or lock the handle with the collar in both the locked and withdrawn positions, although the locking collar member will not dislodge from the wedged or locked position until the cylinder rod is again extended to release the locking member, the pin is thereafter manually removed and the handle used to retract the operating rod and pivot the blocking member away from the cylinder rod. In this manner, a locking member can be pivoted in and out of position on either side of the tailgate as desired to maintain the partially open position of the tailgate. The tailgate lock-open mechanism of the invention is designed readily retrofit on existing systems. The system is designed to serve as a primary positive closure preventing device, but preferably devices already provided or available should be used in conjunction with the system to provide the added safety of a redundant system.